Sealing materials, such as liquid epoxy, are commonly employed to mount the end of a glass or optical fiber in an assembly such as a fiber optic connector. One attribute of liquid epoxy is that is it difficult and time consuming to work with. Generally, two different compounds must be thoroughly mixed in a proper ratio for a predetermined time, then placed into a syringe which is used to apply the mixed compounds as desired. Each of these steps is technique dependant, requiring an attentive, experienced technician to achieve consistent results. Catalytic compounds have the distinct disadvantage of forcing a technician to rush to apply the mixed materials before they set or become difficult to apply. With respect to fiber optic connectors, a portion of the connector is generally filled with the epoxy and the fiber is passed therethrough. After passing the fiber through the liquid epoxy, the fiber must be threaded into a ferrule, a task made more difficult by the viscous liquid. Not infrequently, some of the liquid epoxy is inadvertently deposited on surfaces that must remain epoxy free, necessitating clean-up with an alcohol pad, for example.
An alternative to liquid epoxy is an epoxy preform. Epoxy preforms are solid shapes of one-part epoxy, stable at room temperatures. When exposed to elevated temperatures, they melt to form a rigid seal. Epoxy preforms can be configured in many shapes, such as rings or tubes, and are fabricated with dimensions having .+-.0.002" or tighter tolerances depending upon a particular application. Advantages of epoxy preforms include ease of use and application, consistent quality and quantity, as well as minimal waste and spillage.
U.S. Pat. No. 4,984,865 to Lee et al., discloses a fiber optic connector that includes a thermoplastic slug disposed in a hollow of a connector body. The thermoplastic slug has a longitudinal opening through which an optical fiber is passed. Heat is applied to liquify the thermoplastic slug to cause it to bond to the optical fiber and the wall of the hollow. However, thermoplastic epoxies are disadvantageous in applications wherein the fiber optic connector is subjected to heat, as the epoxy can soften or even become displaced, thereby destroying the connection, rendering the fiber unstable and susceptible to breakage, and permitting contaminants to enter the connector body.
Further with respect to the connector disclosed by Lee, the thermoplastic slug is not positively retained within the hollow, allowing the slug to either be partially displaced, thereby placing the longitudinal opening through the slug, having a diameter not much greater than the fiber, out of alignment with an opening in a ferrule against which the slug abuts. Worse yet, the connector configuration in Lee can easily permit the slug to become completely dislodged, and possibly lost, if the opening in the connector through which the slug is introduced is not maintained in a substantially upright orientation.
A need exists for a fiber optic connector which facilitates rapid, yet precise connection of an optical fiber with a connector body, while providing a heat tolerant epoxy seal between the fiber, the connector body, and a ferrule.